Our three oldest bathe together, so the youngest in the tub is 25 months (and he sits in his booster seat because he hates the feeling of the bathtub). I wouldn't even turn my back on them personally, let alone actually leave the room.
Our eldest is very responsible, nurturing and reasonably cautious with his brothers, but I still wouldn't leave them. I have forgotten towels before, and I just apologise when they're done and have to stand freezing on the bathmat while I go get them (I let the water out before they're actually out, and by the time they're all on the mat, it's gone- sometimes I spray them down before they get out too). Anyway, they mostly have had showers more regularly for messes than actual baths (and the baths ended when we had tailings come out of our faucet...
I would NEVER leave a 19 month old. I actually felt a bit of that sick feeling I get when I am about to cry about something really terrible happening to a child when I read that
. Sorry. Please talk to your dh.
By the way, over about 3 yrs, I don't think that the age matters as much as what you know about your child and the set-up of your bathroom, and whatever other factors you would consider. Some children are very cautious and compliant and wouldn't do anything that wasn't explicitly allowed and so leaving for a minute wouldn't necessarily be dangerous for them; I suspect those are few and far between, or I just haven't met many (perhaps they run when they see our brood comin'
I wouldn't leave someone else's child at that age; sometimes that's the measure I use when I can't decide if something is safe or not for our dc- it helps me to gain perspective and to remember that people are dynamic and sometimes (heehee) behave in unpredictable ways.